IIRC amigabasic uses the upper 8-bit of addresses to store some information. That means it won't work with memory above 24-bit (0xffffff or 16MB). Assuming you apply the patch mentioned earlier and disable all memory above the limit, it could work.
If you have a 32-bit CPU there could be problems doing that. Any accesses to addresses above 16MB (as AmigaBASIC may use) could result in a bus error, or at least not return the correct values.
One workaround could be to use SetCPU with its FASTROM option, along with specifying BITS 24. That should (hopefully) cause the MMU to remap all accesses above 16MB to the lower 16MB region.
At least when I tried than in WinUAE with a 68030+MMU config and no RAM above 16MB, all the BASIC demos on the Extras disk seemed to work fine. But having said that, they all seemed to work fine without using SetCPU! But with some Zorro III RAM, on clicking one of the BasicDemos icons, AmigaBASIC just reports file not found. After running NoFastMem, opening the BasicDemos icons did work properly.
Maybe AmigaBASIC sanitises its addresses, i.e. always clears the upper 8 bits before the memory access. So the crucial thing is to have AmigaBASIC only work with memory in the lower 16MB. You could use NoFastMem for that, but if you have some Zorro II fast RAM (or $C00000 slow RAM) that's a waste of chip RAM. If there's a utility like NoFastMem, but which forces all allocations to use the MEMF_24BITDMA flag, you could run that instead before loading AmigaBASIC.
